1. Field of the Invention
The present invention relates to a motor and, more particularly, to a motor having a non-metal shaft tube.
2. Description of the Related Art
Modern available motors are mainly categorized as having either a metal or a plastic shaft tube. Referring to FIG. 1, Taiwan Patent Publication No. 384947 discloses a motor having a metal shaft tube. In FIG. 1, a motor 7 comprises a metal shaft tube 71 mounted on a casing seat 72, as well as a stator seat 73 closely fitted to an outer circumferential wall of the metal shaft tube 71. A plurality of bearings 74 is equipped inside the metal shaft tube 71, and a rotor 75 is coupled to the bearings 74.
However, it is difficult to manufacture and process the motor 7. Besides, additional manpower is required to mount the metal shaft tube 71 on the casing seat 72, making it costly to produce the motor 7.
Referring to FIG. 2, a motor having a plastic shaft tube is disclosed. The motor 8 mainly comprises a base 81, a stator 82 and a rotor 83. The base 81 has a plastic shaft tube 811 with a bearing 812 equipped therein. The stator 82 is coupled with an outer circumferential surface of the plastic shaft tube 811. The rotor 83 is rotatably coupled with the bearing 812. Based on this, the stator 82 is capable of driving the rotor 83.
The plastic shaft tube 811 of the motor 8 may be integrally manufactured in a manner of injection molding, which is particularly advantageous over the motor 7 in terms of manufacturing, assembly and cost. Although the motor 8 does not have the problems presented by the motor 7, other problems are raised. Specifically, during assembly, the plastic shaft tube 811 and the bearing 812 are coupled with each other in a close fitting manner. If the plastic shaft tube 811 and the bearing 812 are excessively fitted with each other, the bearing 812 will be excessively compressed by the plastic shaft tube 811, causing the bearing 812 to be damaged, deformed, shifted, etc. As a result, the lifespan of the motor 8 is reduced.
To avoid the above potential problems of the motor 8, Taiwan Patent Publication No. 519259 discloses a motor as shown in FIG. 3. In FIG. 3, a traditional motor 9 comprises an axial seat 91 having a cannular groove 911 formed thereon. Based on this, an inner circular wall 912 and an outer circular wall 913 are formed on the axial seat 91. The inner circular wall 912 is provided to receive a bearing 92, and the outer circular wall 913 is provided to fit a stator seat 93. A baffle ring 94 is fitted in the cannular groove 911. In this way, the baffle ring 94 may support the outer circular wall 913, preventing the bearing 92 from being excessively compressed by the axial seat 91 when the axial seat 91 is deformed. However, the structure of the axial seat 91 is somewhat complex, making it difficult to mold the axial seat 91. Therefore, there is a need to overcome the problem.